Folding bicycle frame



FIG. 1 is a perspective view of a folding bicycle frame in accordance with my design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a reference view of a folding bicycle frame thereof.

The broken lines are shown for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a folding bicycle frame, as shown and described. 